Nomodule Shim

<script>
    // https://gist.github.com/samthor/64b114e4a4f539915a95b91ffd340acc
    (function() {
        var check = document.createElement('script');
        if (!('noModule' in check) && 'onbeforeload' in check) {
            var support = false;
            document.addEventListener('beforeload', function(e) {
                if (e.target === check) {
                    support = true;
                } else if (!e.target.hasAttribute('nomodule') || !support) {
                    return;
                }
                e.preventDefault();
            }, true);
            check.type = 'module';
            check.src = '.';
            document.head.appendChild(check);
            check.remove();
        }
    }());
</script>